Search results

The mathematical models that can be used to describe cutting by lapping need to take into account the shape of the abrasive grain, the modality of material removal, the number of grains in contact etc. [3].
By the repeated action of numerous abrasive grains the number of cracks grows, they deepen and overlap thus generating the material removing erosion process [6], [7].
Dependence of grain penetration depth on grain dimensions Only the large abrasive grains participate in cutting the workpiece surface, namely particles with dimensions falling into the interval [δ; dmax].
Fig. 7 presents the case of lapping with a F400 micropowder (micro grains) F400, with an average abrasive grain dimension of dmed = 17.3 ± 1 µm.
(14) Of the total of abrasive grains only fraction Fp participates in cutting, hence the volume of the effectively cutting grains is:

MDF to a total strain of 1.2 results in the formation of large number of strain-induced low-angle boundaries within initial coarse grains.
This process rapidly develops with an increase in the number of turns from 0.5 to 1.
The number of new recrystallized grains and their volume fraction increases upon further straining to 3 turns.
The recrystallized fraction gradually increases when the number of HPT turns increase to 1.
The microstructure contains large initial grains with great number of low-angle boundaries after 1 ECAP pass.

The metal is composed of a plurality of grains.
For the finer the grain, the more plastic deformation may be dispersed in the grains.
Assuming that the area and force are the same, the force apportioned to each grain size is less and the fatigue crack growth rate is decreased if the grain size is small; on the contrary, the force apportioned to each grain size is great and the fatigue crack growth rate is increased if the grain size is large.
In the same area, each grain is allocated more force if the grain size is larger, and the number of grain is greater.
On the contrary, each grain is allocated less force.

Cube grains are evidently observed in (a) 493K map though their number and size are not so large.
The grains involve numbers of cube ones.
In both samples, the total number of grains decreases gradually during microstructural evolution.
The increase in the number of cube grains for both samples in lower temperature range means that numbers of cube grains appear from inside to surface as described above.
The numbers of S- and Cu-oriented grains decrease with evolving cube texture in both samples.

It was found that addition of Ti at this level resulted in grain refinement of aluminum structure whereas addition of Zr alone resulted in grain coarsening of Al structure while it resulted in grain refinement when it is added in the presence of Ti.
As mentioned before Zr, Ta and Cr have a poisoning effect, i.e. the grains become larger when the grain refiner is added or reducing the grain refining efficiency of Al-Ti and Al-Ti-B master alloys.
Determination of the Wear of Aluminum and its Microalloys The basis of wear theories was attempted to explain the wear process on a microscopic scale and to relate the magnitude of the wear to the material properties, and to the number and nature of the local encounters.
The first such theory was proposed which related the wear rate to the number of interatomic encounters between the opposing surfaces [11].
Addition of Ti resulted in grain refinement of commercially pure aluminum whereas addition of Zr resulted in grain coarsening.

As shown in figure 4-a, when the bath temperature from 1600℃ to 1700℃, the number of grain and the average radius changes by a big margin, which the grain number reduces about 13.4%, average grain radius increases about 3.42%.
The grain number, when the water lever is 7.5m3/h, has improved 8.45%, and the average grain radius decreases by 12.86% more than the 5m3/h lever.
Therefore, it can be seen, that improving the cooling intensity can make the growth of columnar crystals smaller, and the grain number increase, and the average grain radius decreases.
The number of nucleation will be increase in the lower bath temperature, which will help the refinement of the columnar grain of the ESR solidification organization
(3) On the optimized conditions, the number of the grain nucleation is improved about13.8%, the average grain radius is reduced about 10.61%, the grain size of solidification structure has been greatly refined, and the uniformity of the organization is improved.

The results show that it is feasible to fabricate nanocrystalline copper by explosively dynamic plastic deformation of coarse-grained copper and the grain size of the NC copper can be controlled less than 100 nanometer; higher strain at high strain rate is beneficial to the grain refining; the distribution of the grain size is not uniform along the loading direction; dynamic yield strength of the NC copper enhences with the decreasing of the average grain size and increasing of the strain rate.
Analysis of the grain sizes The mean grain size of the NC copper samples were determined by XRD of D/Max2500VL/PC.
According to the Scherrer formula, the grain size can be obtained[15].
According to the Scherrer equation, the mean grain size of sample 1 was obtained the number was 31.4nm, by the same way, the mean grain size of all the other samples can be obtained.
So Ls-dyna3d finite element programm is used in this paper to research the effect of strain on the grain sizes and distribution rule of the grain sizes.

Due to the grain itself is a living organism, constantly engage in life and biochemistry movement, so as to consume the nutrients of grain particles in the process of grain storage; and at the same time, insects, mold, mice and sparrow in the grain bulk ecosystems also will do harmful it and cause the food reduction in the storage.
There has great significance to guarantee food security of the country by improving the level of grain storage, combining advanced computer technology with grain storage work and designing and developing appropriate expert system of grain storage.
This system can warn some factors which are not conducive to grain storage, help to improve the maintenance efficiency and management level of grain storage and reduce the loss of the grain in storage process.
Figure2 The flow chart of inference mechanism In inference process , the system matches the currently known facts with knowledge in the knowledge base constantly, at the same time a prerequisite of a number of knowledge may be satisfied that the knowledge are matched successfully and form the conflict.
Grain Processing. 2011,36(1): 70-73

For GAM a grain definition is needed.
A grain is defined by an area boundary by a continuous boundary above 5° misorientation: GAM representing average point-to-point misorientation inside such a grain.
Seshadri, Relative effect(s) of texture and grain size on magnetic properties in a low silicon non-grain oriented electrical steel, Journal of Magnetism and Magnetic Materials 264 (2003) 75–85 [2] Chikara Kaido, Spiral core made of grain-oriented electrical steel sheet, Electrical engineering in Japan, Vol. 118, No. 3,1997 [3] Yu.
Landgraf, Effect of deformation and annealing on the microstructure and magnetic properties of grain-oriented electrical steels, Journal of Magnetism and Magnetic Materials 304 (2006) e617–e619 [9] Ken-ichi Yamamoto and Yasumasa Yamashiro, Effect of compressive stress on hysteresis loss and magnetostriction of grain oriented Si–Fe sheets, journal of applied physics, volume 93, number 10, 2003 [10] G.
Groma,X-ray line broadening due to an inhomogeneous dislocation distribution, Physical Review B, Volume 57, Number 13

Accordingly, it was evident that multi-forging was very effective on grain refinement and grain size uniformity.
Reaching the mushy zone, liquid is formed by preferential melting at grain boundaries with high energy state, and penetrates into high angle boundaries of recrystallized grains.
The RAP microstructure consisted of equiaxed grains with the presence of liquid phase at some grain boundaries.
The increment of the multi-forging strain accelerates recovery and recrystallization kinetics and provides the larger number of recrystallization sites.
In addition to high angle grain boundaries, the liquid formed in grains can be penetrated into low angle boundaries formed by multi-forging at higher RAP temperature.